Field of the Invention
The present invention relates to a device for delivering and dosing a liquid additive. Such a device may be used, for example, in a motor vehicle to feed a liquid additive to an exhaust-gas treatment device of the motor vehicle. The invention also relates to a motor vehicle having the device.
In motor vehicles with diesel internal combustion engines, exhaust-gas treatment devices are used into which a liquid additive is fed. The liquid additive then serves, for example, to reduce nitrogen oxide compounds in the exhaust gas of the internal combustion engine. This takes place with the aid of the method of selective catalytic reduction (SCR method). In the SCR method, a urea-water solution is typically used as a liquid additive and the urea-water solution is converted in the exhaust gas to form ammonia. The conversion of nitrogen oxide compounds in the exhaust gas into non-harmful substances such as water (H2O), nitrogen (N2) and/or carbon dioxide (CO2) then takes place with the aid of the ammonia. At present, a 32.5% (by weight) urea-water solution which is available under the trademark AdBlue® has become established as a liquid additive. A liquid additive used for the purpose of exhaust-gas purification is often also referred to as a reducing agent or a reducing agent precursor.
A device for delivering and dosing a liquid additive for a motor vehicle should as far as possible function in the manner of an (autonomous) black box system. A black box system means a system to which a dosing demand for dosing the liquid additive is transmitted, and which thereupon delivers a liquid additive quantity corresponding to the dosing demand from a tank. In order to satisfy the demand, it is advantageous for electronic components to be provided within the device, which electronic components correspondingly process the dosing demand in order to control, operate, etc. the components of the dosing device accordingly. For example, the information regarding a demanded quantity of liquid additive may be converted into a control variable for the operation of a delivery pump in the device.
Furthermore, a device for delivering a liquid additive should be manufactured with low costs and be as easy as possible to maintain.